Improvement in piston-packing



,itu-ital time `gallant (titille.

Leners Patat No. 101,792, dma Apt/zz 12, 1870.

IMPROVEMENT IN PISTON-PACI-KING.

The Schedule referred to in these Letters Patent and making part of thesame.

To all to whom these presents shall come:

Beit known that I, ELLERY A. WALKER, of Hyannis, in the county ofBarnstable and State of Massachusetts, have made an invention of a newand useful Manufacture of Pistons for Steam-Enginery; and do herebydeclare the following to be a full, clear, and exact descriptionthereof, due reference being had to the accompanying drawings makingpart of this specification, and in which- Figure 1 is an elevation;

Figure 2, a vertical section; and

lFigure 3, an end view, with the outer cap rennived, of a pistonembodying my improvements.

The class of pistons upon which this invention is founded is that knownas sectional ring-packing pistons, or those in which a series ofmetallic rings or sections of rings are employed, and which, by theirpressure against the interior of the cylinder of the engine, serves toprevent clandestine passage of steam between the two.

Previous to the origin of the improvements herein to be described, thesesectional rings have been ex-` panded in two ways: one by the directpressure of the steam, admitted behind them in small quantities from thecylinder, and the other by the pressure of springs behind them.

The force of the steam has been found to exert too sudden and injurious'action upon the cylinder, and

' this mode of expanding the sectional rings has been generallyabandoned.

The action of the springs is subject to changes in power, owing to thereduction of the periphery of the` packing-rings under wear, and, aspistons have heretofore been produced, must be frequently set out bymeans ofV set-screws applied to them for the purpose, this actnecessitating frequent removal and dismemberment of the piston. It iswell known to persons accustomed to the action of steam-engines, thatthe tendency ofthe piston to tilt inthe cylinder at one extreme of itstraverse, and, to some extent, both, wears such cylinder at one point inits circumference, often requiring renewed boring out, or permittingescape of steam past the"A piston, owing to the fact that the rings,which perform the oiice of packing the piston, also form its entirebearing-surface. A

Attempts have been made to remedy this by the employment of a centralring of soft metal, located midway between the ends of the piston, forthe purpose of centering the piston. But when the latter tilts, as abovespecified, it is the ends o f the piston which are liable to wear thecylinder, and therefore a inating this invention, which comprises thesubject matter of these Letters Patent, has been to create upon theperiphery of the piston, at or near each end, a bearing orsupporting-surface or surfaces, wh-ich shall receive the generalwear'upon such piston, by this means relieving the packing-rings of thisduty, which has heretofore devolved upon them, and requiring them onlyto preserve a tight joint between the piston and cylinder.

By effecting this result I economize, to a great and valuable extent,the unequal wear of the piston upon l the component parts of which areshown in the head or block at l), the outer plates or caps at c c, andthe sectional orsplit packing-rings at d d, such parts be ing producedand combined in manner substantially similar to others in use, withexceptions hereinafter stated. e

v In carrying out .my invention, I form each of the y two end caps or.plates c c,whicl1 confine the packing.-

rings in place, with a circnmscribing peripheral channel'or groove, e,and I ll this channel with Babbitt or; other soft metal, f, permittingof an excess of the same beyond the periphery of the cap, in order thatit (the soft metal) alone shall come in contact with theV bore ofthecylinder, with the exception of the packing-rings d (l.

These packing-rings encircle, or nearly so, the periphery of thepiston-block, a shallow intervening an-v nular chamber, g, being leftbetween Vthe twosto-receive a plurality of curved plate-springs, Vh lt,&`c.'," formed and disposed as shownin iig.3 of the drawings; that is,asexerting a pressure between-the piston-head b andthe packing-ringsY'al-1d, andforcing the latter into contact with the bore of thecylinder.

- Owing to the fact that'the cap-'platesn 'c c'of'the piston, o r theirsoft metal-ringsoribsservetoisustain the `thrusts^upo`nsuch piston','and maintaitprper position within the cylinder, the wear exerted uponthe packing-rings is, comparatively, very slight, and no set-screws areneeded to compensate for the increase in area of the annular i'nclosureg which now ensues, owing to the rapid wear upon the rings and' the boreof the cylinder, and thus I avoid the present unavoidable stoppage ofthe engine, the loss-of time, and the annoyance of removing anddismernbering the4 piston.

As the packing-rings, combined with the pistouhead in the presentinstance, are of one piece of metal with the abutting ends, some meansbecomes necessary for preventing turning of the same about thepiston-head, in order to avoid coincidence of the openings of the two.

In the drawings hereto annexed I exhibit a means of eiectin g thispurpose, which consists in fixing upon the inner face of each ring twoprojections or pins, 'i o, such pins straddling a .fin or rib, j,extending outward from the piston-head.

Although I have, in the. accompanying drawings, exhibited the-soft metalas a continuous ring, encircling each end plate of the piston, it maybe. disposed in sections, as practice has ldemonstrated that abearing-sulface for eachv end of the piston, at the top and bottom, willbe suiicient.

Having described my invention, I would state that ing, and the wholeoperating as hereinbefore set forth' l ELLERY A. WALKER.

Witnesses FRED. CBUTIs, E. GRIFFITH.

I do not claim, broadly, the formation upon the pisc c, the latter beingprovided with a soft-metal bear-

